A reduction in size of information processing equipment such as a notebook personal computer and a cellular phone has been desired. A reduction in size and weight of a laminate provided with electronic parts such as an LSI has also been desired. In order to reduce the size and weight of such a laminate, it is necessary to reduce the conductor width, through-hole diameter, and plating thickness. However, a reduction in plating thickness may cause plating cracks to occur due to a thermal shock. This may lead to a decrease in connection reliability. For this reason, a laminate is required to possess heat resistance and a small coefficient of linear expansion in the thickness direction.
In recent years, a high-melting-point solder that does not contain lead is becoming mainstream from the viewpoint of environmental regulations. Therefore, laminates are required to exhibit lead-free heat resistance to a degree not exhibiting cracking under severe conditions of about 290° C. according to the IPC T-288 test. Laminates are also required to exhibit flame retardancy.
A laminate using a naphthalene-modified epoxy resin has solder heat resistance and a small coefficient of linear expansion in the thickness direction (for example, JP-A-5-301941). On the other hand, the naphthalene-modified epoxy resin has poor adhesion to a conductor circuit metal. The naphthalene-modified epoxy resin also has poor lead-free heat resistance.
A resin composition that contains an epoxy resin containing a dicyclopentadiene-type epoxy resin and a triazine-modified novolac resin may have solder heat resistance, a small coefficient of linear expansion in the thickness direction, and adhesion to a conductor circuit metal (JP-A-2005-336280). However, such a resin composition has poor flame retardancy. Flame retardancy can be improved by increasing the nitrogen content. However, an increase in nitrogen content decreases the lead-free heat resistance. Thus, it is impossible to satisfy flame retardancy and lead-free heat resistance at the same time.
An object of the present invention is to provide a resin composition which can produce a laminate that exhibits excellent flame retardancy, solder heat resistance, and lead-free heat resistance, has a small coefficient of linear expansion in the thickness direction, and has excellent adhesion to a conductor circuit, a prepreg and a laminate using the resin composition.